I've been back and forth on this one and finally today tossed the 4 oz Aquamira for a Clear Eyes bottle filled with bleech. I started counting the number of drops in the 1 oz bottle, got to 200 and quit. I'm guessing about 500 drops in a Clear Eyes bottle or about 250 liters of water...should get me to ME. Saving that 3 oz will allow me to take a real coffee cup.